* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: clamp(13px, 1.2vw, 16px);
}

body {
    font-family: 'Microsoft YaHei', 'PingFang SC', -apple-system, sans-serif;
    background: linear-gradient(135deg, #eaf2fb 0%, #f8fbff 45%, #edf4fd 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.login-container {
    width: 100%;
    max-width: 420px;
    padding: 20px;
}

.login-card {
    background: #ffffff;
    border-radius: 18px;
    padding: 2.5rem 2.25rem;
    border: 1px solid #dbe4ef;
    box-shadow: 0 22px 48px rgba(15, 23, 42, 0.1);
}

.login-header {
    text-align: center;
    margin-bottom: 2rem;
}

.login-header h1 {
    color: #3b82f6;
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    letter-spacing: 2px;
}

.login-header p {
    color: #6b7785;
    font-size: 0.875rem;
}

.alert {
    padding: 0.625rem 0.875rem;
    border-radius: 8px;
    margin-bottom: 1rem;
    font-size: 0.875rem;
}

.alert-error {
    background: rgba(214, 69, 69, 0.12);
    color: #d64545;
    border: 1px solid rgba(214, 69, 69, 0.25);
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    color: #4b5563;
    font-size: 0.875rem;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.form-group input {
    width: 100%;
    padding: 0.75rem 1rem;
    background: #f9fafb;
    border: 1px solid #dbe4ef;
    border-radius: 8px;
    color: #1f2933;
    font-size: 0.9375rem;
    transition: all 0.3s;
    outline: none;
}

.form-group input:focus {
    border-color: #3b82f6;
    box-shadow: 0 0 12px rgba(59, 130, 246, 0.15);
}

.form-group input::placeholder {
    color: #9aa4b2;
}

.btn-login {
    width: 100%;
    padding: 0.8125rem;
    background: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
    border: none;
    border-radius: 8px;
    color: white;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    letter-spacing: 4px;
    margin-top: 0.5rem;
}

.btn-login:hover {
    background: linear-gradient(135deg, #4c8bf8 0%, #2f6af0 100%);
    transform: translateY(-1px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.25);
}

.btn-login:active {
    transform: translateY(0);
}

.login-footer {
    margin-top: 1.5rem;
    text-align: center;
    border-top: 1px solid #e2e8f0;
    padding-top: 1rem;
}

.login-footer p {
    color: #7b8896;
    font-size: 0.75rem;
    line-height: 1.8;
}